Ask question

Ask question

All categories

3 years ago

10

A bag contains 9 marbles: 3 are green, 4 are red, and 2 are blue. Christine chooses a marble at random, and without putting it b

ack, chooses another one at random. What is the probability that both marbles she chooses are blue? Write your answer as a fraction in simplest form

1 answer:

elena55 [62]3 years ago

3 0

Answer:

there is a 1/4 possibility that the marbles will blue

Step-by-step explanation:

but it might also be red because there are so many red marbles (4) it might com out as red.

You might be interested in

According to a Yale program on climate change communication survey, 71% of Americans think global warming is happening.† (a) For

SpyIntel [72]

Answer:

a) 0.2741 = 27.41% probability that at least 13 believe global warming is occurring

b) 0.7611 = 76.11% probability that at least 110 believe global warming is occurring

Step-by-step explanation:

Binomial probability distribution

The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

$P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}$

In which $C_{n,x}$ is the number of different combinations of x objects from a set of n elements, given by the following formula.

$C_{n,x} = \frac{n!}{x!(n-x)!}$

And p is the probability of X happening.

The expected value of the binomial distribution is:

$E(X) = np$

The standard deviation of the binomial distribution is:

$\sqrt{V(X)} = \sqrt{np(1-p)}$

Normal probability distribution

Problems of normally distributed samples can be solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the zscore of a measure X is given by:

$Z = \frac{X - \mu}{\sigma}$

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

When we are approximating a binomial distribution to a normal one, we have that $\mu = E(X)$ , $\sigma = \sqrt{V(X)}$ .

In this problem, we have that:

$p = 0.71$

(a) For a sample of 16 Americans, what is the probability that at least 13 believe global warming is occurring?

Here $n = 16$ , we want $P(X \geq 13)$ . So

$P(X \geq 13) = P(X = 13) + P(X = 14) + P(X = 15) + P(X = 16)$

In which

$P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}$

$P(X = 13) = C_{16,13}.(0.71)^{13}.(0.29)^{3} = 0.1591$

$P(X = 14) = C_{16,14}.(0.71)^{14}.(0.29)^{2} = 0.0835$

$P(X = 15) = C_{16,15}.(0.71)^{15}.(0.29)^{1} = 0.0273$

$P(X = 16) = C_{16,16}.(0.71)^{16}.(0.29)^{0} = 0.0042$

$P(X \geq 13) = P(X = 13) + P(X = 14) + P(X = 15) + P(X = 16) = 0.1591 + 0.0835 + 0.0273 + 0.0042 = 0.2741$

0.2741 = 27.41% probability that at least 13 believe global warming is occurring

(b) For a sample of 160 Americans, what is the probability that at least 110 believe global warming is occurring?

Now $n = 160$ . So

$\mu = E(X) = np = 160*0.71 = 113.6$

$\sigma = \sqrt{V(X)} = \sqrt{np(1-p)} = \sqrt{160*0.71*0.29} = 5.74$

Using continuity correction, this is $P(X \geq 110 - 0.5) = P(X \geq 109.5)$ , which is 1 subtracted by the pvalue of Z when X = 109.5. So

$Z = \frac{X - \mu}{\sigma}$

$Z = \frac{109.5 - 113.6}{5.74}$

$Z = -0.71$

$Z = -0.71$ has a pvalue of 0.2389

1 - 0.2389 = 0.7611

0.7611 = 76.11% probability that at least 110 believe global warming is occurring

3 0

2 years ago

Which two ratios form a proportion?

Alex17521 [72]

Step-by-step explanation:

4 and 5 is one 20/25

3 0

3 years ago

Read 2 more answers

The Burj Khalifa, the tallest building in the world with 163 floors, is having problems with its air conditoning system. It is s

LuckyWell [14K]

This question was already asked so I will put the answer here.

The correct answer is letter (B) {1,2,3,4,...,163}.The burj khalifa the tallest building in the world with 163 floors, is having problems with is air conditioning system. It is suspected that thedifference is air pressure between the first floor and the top floor is the problem. normal pressure for the bottom floor is 14.7psi. a building engineer uses the function p to analyse pressure p(f) represents the pressure on each floor, where f is the floor number.

7 0

2 years ago

Read 2 more answers

Which of the following statements about the similarity between rectangles and squares is not true?

pshichka [43]

Answer:

Both rectangles and squares have four sides of equal length

7 0

3 years ago

If a=58, then What is 59÷a?

algol [13]

To solve this problem we would plug 58 into the equation for a
Making the equation 59÷58

59÷58=1.0172413793103
Or
1.02

6 0

3 years ago